Chromogenic materials employing fluoran compounds

ABSTRACT

The fluoran compounds of the formula (I) are new red color forming chromogenic dyes.    &lt;IMAGE&gt;  (I)  wherein R represents an isobutyl or isopentyl group, R1 represents a hydrogen or halogen atom or an alkyl group, R2 represents a hydrogen or halogen atom or an alkyl group, R3 represents a hydrogen atom, and R4 represents a hydrogen atom, or R4 and R1 as well as R2 and R3 taken together with the carbon atoms to which they are attached may form a benzene ring which may be substituted with a halogen atom. They are used, together with an acidic developer, in chromogenic recording materials for use in pressure sensitive copying paper, heat-sensitive recording paper and thermo-sensitive, reversible color changing composition.

FIELD OF THE INVENTION

This invention relates to red color forming chromogenic fluorancompounds which exhibit excellent color forming performance by theaction of acidic substances brought into intimate contact therewith andto chromogenic recording materials comprising the same.

BACKGROUND OF THE INVENTION

At present, recording materials which comprise chromogenic dyes whichare colorless or substantially colorless in themselves but form colorsby the action of acidic substances brought into intimate contacttherewith (said dyes are hereinafter called "chromogenic dyes") and saidacidic substances (color developers) which permit said chromogenic dyesto form colors have been extensively used for, e.g., pressure-sensitivecopying papers, heat-sensitive recording papers and the like. Keepingpace with the speeding-up of the services of communication recordingdevices such as facsimile, it is desired that the color developing speedof the heat-sensitive recording papers used in facsimile is accelerated.For heat-sensitive recording papers for use in facsimile, there havebeen mostly used black color forming chromogenic dyes. However, rescolor forming chromogenic dyes are sometimes used in admixture with theblack color forming chromogenic dyes in order to effect tone adjustmentof formed color from said black color forming chromogenic dyes used. Onthat account, it is desired that the red color forming chromogenic dyesas well as the black color forming chromogenic dyes are improved inchromogenic characteristics thereof.

Heretofore, 3-diethylamino-6-methyl-7-chlorofluoran of the formula,##STR2## 3-diethylamino-7-chlorofluoran of the formula, ##STR3## or3-diethylamino-7,8-benzofluoran of the formula, ##STR4## has preferablybeen used as a red color forming chromogenic dye for use in toneadjustment of the black color forming chromogenic dyes.

SUMMARY OF THE INVENTION

Now, we have found that the fluoran compounds represented by the formula(I) are red color forming chromogenic dyes excellent in chromogeniccharacteristics. ##STR5## wherein R represents an isobutyl group or anisopentyl group,

R₁ represents a hydrogen or halogen atom or an alkyl group,

R₂ represents a hydrogen or halogen atom or an alkyl group,

R₃ represents a hydrogen atom, and

R₄ represents a hydrogen atom, or R₄ and R₁ as well as R₂ and R₃ takentogether with the carbon atoms to which they are attached may form abenzene ring optionally substituted with a halogen atom.

BRIEF DESCRIPTION OF THE DRAWINGS

The FIGURE is NMR spectrum of 3-N-isobutyl-ethylamino-6-ethylfluoran.

DETAILED DISCLOSURE OF THE INVENTION

The fluoran compounds represented by the formula (I) are prepared byreacting in sulfuric acid one mole of a benzoic acid derivativerepresented by the formula ##STR6## wherein R is as defined above, withapproximately one mole of a phenol derivative of the formula ##STR7##wherein R₁, R₂, R₃ and R₄ are as defined above, and R₅ represents ahydrogen atom or a lower alkyl group. The concentration of sulfuric acidused is preferably 80% or higher, and the reaction is carried out at atemperature of 100°-120° C. for 4-8 hours, whereby the end products canbe obtained.

In the formulas (I) and (III), the alkyl group as R₁ preferably includesthose of 1-6 carbon atoms, which may be branched, and the alkyl group asR₂ preferably includes those of 1-8 carbon atoms which may be branched.

Typical examples of the compounds represented by the formula (I) thusprepared are shown together with their respective physical properties inTable 1.

                                      TABLE 1                                     __________________________________________________________________________    Compound                                     Melting     Developed            No.   R            R.sub.4   R.sub.1                                                                          R.sub.2  R.sub.3                                                                           point (°C.)                                                                        Color                __________________________________________________________________________           ##STR8##    H         CH.sub.3                                                                         Cl       H   186.2˜187.8                                                                         Vermilion            2                                                                                    ##STR9##    H         H  Cl       H   149.1˜150.6                                                                         Vermilion            3                                                                                    ##STR10##   H         Cl Cl       H   155.6˜158.0                                                                         Vermilion            4                                                                                    ##STR11##   H         H                                                                                 ##STR12##                                                                             H   185.0˜186.4                                                                         Vermilion            5                                                                                    ##STR13##   H         H  CHCHCHCH     192.7˜193.7                                                                         Pink                 6                                                                                    ##STR14##   H         H                                                                                 ##STR15##   188.0˜189.8                                                                         Pink                 7                                                                                    ##STR16##   H         CH.sub.3                                                                         Cl       H   156.5˜159.0                                                                         Vermilion            8                                                                                    ##STR17##   H         H  Cl       H   149.0˜151.0                                                                         Vermilion            9                                                                                    ##STR18##   H         C.sub.2 H.sub.5                                                                  H        H   Difficult to                                                                              Vermilionze          10                                                                                   ##STR19##   CHCHCHCH     H        H   158.8˜160.7                                                                         Pink                 __________________________________________________________________________

Tables 2 and 3 respectively show a comparison of chromogeniccharacteristics between the present novel fluoran compounds and theconventionally used red color forming fluoran compounds when they areapplied to heat-sensitive recording papers.

                  TABLE 2                                                         ______________________________________                                        Heat-sensitive                                                                           Color development temperature (°C.)                         recording paper                                                                          95     100    110  120   130  150  180                             ______________________________________                                        I (Example 11)                                                                           0.08   0.11   0.15 0.35  0.78 0.99 0.99                            II (Compara-                                                                             0.08   0.10   0.12 0.19  0.50 0.94 0.98                            tive Example 1)                                                               ______________________________________                                    

                  TABLE 3                                                         ______________________________________                                        Heat-sensitive                                                                           Color development temperature (°C.)                         recording paper                                                                          85     90     95   100   110  120  130                             ______________________________________                                        III (Example 12)                                                                         0.01   0.22   0.60 0.88  0.94 0.97 0.95                            IV (Compara-                                                                             0.08   0.12   0.40 0.84  0.91 0.90 0.93                            tive Example 2)                                                               ______________________________________                                    

In Table 2, the values indicate color densities, at the respectivetemperatures, of the heat-sensitive recording papers made in Example 11and Comparative Example 1. Similarly, the values in Table 3 indicatecolor densities, at the respective temperatures, of heat-sensitiverecording papers made in Example 12 and Comparative Example 2. For thecolor development, a Dry Heating Tester (manufactured and sold byKishino Science Machinery Co., Ltd.) was used for heating. The colordensity was measured using the Macbeth reflection densitometer. Largervalues for the color density show deeper hues of color.

It is evident from the results in Tables 2 and 3 that the fluorancompounds of the present invention possess excellent color developmentperformance under the influence of heat in comparison with red colorforming chromogenic fluoran compounds used conventionally.

Further, the present compounds are markedly high in solubility inorganic solvents in comparison with the known red color formingchromogenic fluoran compounds as mentioned above. This property is ofgreat advantage to the present compounds when they are used inpressure-sensitive copying papers.

As is clear from the foregoing, the present compounds represented by theformula (I) can be used singly for the preparation of recordingmaterials which form red color. Further, they may be used in admixturewith blue color chromogenic dyes to form blue black color, or they maybe used in admixture with blue color forming chromogenic dyes and greencolor forming chromogenic dyes to prepare recording materials which formblack color. Furthermore, they may be mixed with black color formingchromogenic dyes having color quality slightly tinged with green inorder to obtain a color close to real black.

Blue color forming chromogenic dyes which are usable in admixture withthe present fluoran compounds include, by way of only illustration butnot limitation, those which are listed below.

Crystal violet lactone[3,3-bis(4-dimethylaminophenyl)-6-dimethylaminophthalide],

Benzoyl leucomethylene blue,

5(or 7)-(1-octyl-2-methylindol-3-yl)-5(or7)-(4-diethylamino-2-ethoxyphenyl)-5,7-dihydrofuro (3,4-b)-pyridine-7(or5)-one.

Green color forming chromogenic dyes which are usable in admixture withthe present fluoran compounds include, by way of only illustration butnot limitation, those which are listed below.

3-Diethylamino-5-methyl-7-dibenzylaminofluoran,

3-N-isobutyl-ethylamino-7-dibenzylaminofluoran,

3-N-isobutyl-ethylamino-7-phenylaminofluoran,

3-Pyrrolidino-7-dibenzylaminofluoran,

3-Pyrrolidino-7-phenylaminofluoran.

Black color forming chromogenic dyes which are usable in admixture withthe present fluoran compounds include, by way of only illustration butnot of limitation, those which are listed below.

3-Dimethylamino-6-methyl-7-phenylaminofluoran

3-Diethylamino-6-methyl-7-phenylaminofluoran

3-Diethylamino-6-methyl-7-xylidinofluoran

3-Diethylamino-6-methyl-7-p-butylphenylaminofluoran

3-Diethylamino-6-methyl-7-anisidinofluoran

3-Dipropylamino-6-methyl-7-phenylaminofluoran

3-Di-n-butylamino-6-methyl-7-phenylaminofluoran

3-N-Isopropyl-methylamino-6-methyl-7-phenylaminofluoran

3-N-Isobutyl-ethylamino-6-methyl-7-phenylaminofluoran

3-N-Isopentyl-ethylamino-6-methyl-7-phenylaminofluoran

3-N-Hexyl-ethylamino-6-methyl-7-phenylaminofluoran

3-Dibenzylamino-6-methyl-7-phenylaminofluoran

3-N-Methyl-cyclohexylamino-6-methyl-7-phenylaminofluoran

3-N-Methyl-cyclohexylamino-5-chloro-6-methyl-7-phenylaminofluoran

3-N-n-Pentyl-cyclohexylamino-6-methyl-7-phenylaminofluoran

3-N-Methyl-p-tert-butylcyclohexylamino-6-methyl-7-phenylaminofluoran

3-N-Ethyl-3',3',5'-trimethylcyclohexylamino-6-methyl-7-phenylaminofluoran

3-N-Ethyl-furfurylamino-6-methyl-7-phenylaminofluoran

3-Pyrrolidino-6-methyl-7-phenylaminofluoran

3-Piperidino-6-methyl-7-toluidinofluoran

3-Morpholino-6-methyl-7-p-butylphenylaminofluoran

3-N-Methyl-phenylamino-6-methyl-7-phenylaminofluoran

3-N-Ethyl-phenylamino-6-methyl-7-p-toluidinofluoran

3-N-Ethyl-p-toluidino-6-methyl-7-phenylaminofluoran

3-α-Naphthylamino-6-methyl-7-phenylaminofluoran

3-Dimethylamino-7-N-benzyl-m-trifluoromethylphenylaminofluoran

3-Diethylamino-7-m-trifluoromethylphenylaminofluoran

3-Diethylamino-5-ethyl-7-m-trifluoromethylphenylaminofluoran

3-Diethylamino-5-ethyl-7-m-trifluoromethylphenylaminofluoran

3-Diethylamino-5-chloro-7-m-trifluoromethylphenylaminofluoran

3-Dipropylamino-7-m-trifluoromethylaminofluoran

3-Di-n-butylamino-7-m-trifluoromethylphenylaminofluoran

3-N-Ethyl-p-toluidino-7-m-trifluoromethylphenylaminofluoran

3-Piperidino-7-m-trifluoromethylphenylaminofluoran

3-Pyrrolidino-7-m-trifluoromethylphenylaminofluoran

3-Morpholino-7-m-trifluoromethylphenylaminofluoran

3-N-Methyl-cyclohexylamino-7-m-trifluoromethylphenylaminofluoran

3-N-Benzyl-cyclohexylamino-7-m-trifluoromethylphenylaminofluoran

3-N-Ethyl-furfurylamino-7-m-trifluoromethylphenylaminofluoran

3-N-Ethyl-furfurylamino-6-methyl-7-m-trifluoromethylphenylaminofluoran

3-Diethylamino-7-chlorophenylaminofluoran

3-Diethylamino-7-bromophenylaminofluoran

3-Diethylamino-6-chloro-7-phenylaminofluoran

3-Di-n-butylamino-7-chlorophenylaminofluoran

3-Diethylamino-6-methyl-7-benzylamino-4',5'-benzofluoran

3-N-Methyl-phenylamino-5,6-benzo-7-phenoxyphenylaminofluoran

3-N-Benzyl-phenylamino-5,6-benzo-7-phenoxyphenylamino-3',4',5',6'-tetrachlorofluoran

3-Diethylamino-7-piperidinofluoran

2-Methyl-3-ethylamino-5,6-benzo-7-phenylaminofluoran

3-Diethylamino-6-methyl-7-(α-phenylethylamino)fluoran

3-Dimethylamino-7-(α-phenylethylamino)fluoran

3-N-Butyl-xylidino-6-methyl-7-benzylaminofluoran

3-Pyrrolidino-7-di(p-chlorophenyl)methylaminofluoran

3-Methylpiperidino-7-di(p-chlorophenyl)methylaminofluoran

3-Morpholino-5,6-benzo-7-phenylaminofluoran

3-N-Methyl-cyclohexylamino-5,6-benzo-7-α-naphthylamino-4'-bromofluoran.

In addition to heat-sensitive recording papers and pressure-sensitivecopying papers mentioned previously, chromogenic recording materials ofthis invention which comprise the present fluoran compounds or mixturesthereof with other chromogenic dyes can be used for, e.g., recordingpapers relying on heat-sensitive transfer, electro thermo heat-sensitiverecording papers, papers for electrophotography using toners containingacid substances as developers, ultrasonic wave recording paper,photosensitive printing materials, electron recording paper, stampingmaterials, stamp ink, typewriter ribbons or the like, but not limitingthereto.

Following the same manner as in the case of known chromogenic dyes,heat-sensitive recording papers using the fluoran compounds of thisinvention can be prepared in accordance with such procedures asdisclosed, for example, in Japanese Patent Publns. Nos. 27579/1964,4160/1968 and 14039/1970, or Japanese Patent L-O-P Publn. No. 7087/1984.More particularly, heat-sensitive recording papers excellent in colordeveloping property may be prepared by coating, on the surface ofpapers, a suspension containing finely divided particles of the presentfluoran compounds or mixtures thereof with other chromogenic dyes andcolor developers (acidic substances) in an aqueous solution ofwater-soluble binders, followed by drying. Furthermore, there may beprepared heat-sensitive recording papers having very high sensitivitywhen sensitizers are added to the above-mentioned suspension used forthe preparation thereof. This suspension may further contain fillers,dispersing agents, colored image stabilizers, anti-oxidants,desensitizers, anti-tack agents, defoaming agents, light stabilizers,optical brighteners or the like.

The color formation upon intimate contact of the present fluorancompound with a color developer takes place also on such substratesother than paper as aforesaid, for example, as synthetic fiber fabric,non-woven fabric, synthetic paper or synthetic resin sheet (e.g.,transparent polyethylene sheet).

The color developers include, for exmaple, bisphenol compounds such asbisphenol A, 4,4'-secondary-butylidene-bisphenol,4,4'-cyclohexylidenebisphenol, 2,2'-dihydroxy-diphenyl andpentamethylene-bis(4-hydroxybenzoate); sulfur containing bisphenolcompounds such as 1,7-di(4-hydroxy-phenylthio)-3,5-dioxaheptane;4-hydroxybenzoic acid esters such as benzyl 4-hydroxybenzoate, ethyl4-hydroxybenzoate, propyl 4-hydroxybenzoate, isopropyl4-hydroxybenzoate, butyl 4-hydroxybenzoate, isobutyl 4-hydroxybenzoate,chlorobenzyl 4-hydroxybenzoate, methylbenzyl 4-hydroxy-benzoate anddiphenylmethyl 4-hydroxybenzoate; hydroxy-sulfones such as4-hydroxy-4'-methyldiphenylsulfone,4-hydroxy-4'-isopropoxydiphenylsulfone and4-hydroxy-4'-butoxydiphenyl-sulfone; 4-hydroxyphthalic acid diesterssuch as dimethyl 4-hydroxyphthalate, dicyclohexyl 4-hydroxyphthalate anddiphenyl 4-hydroxyphthalate; such esters of hydroxynaphthoic acid as2-hydroxy-6-carboxynaphthalene; and further hydroxyacetophenone,p-phenylphenol, benzyl 4-hydroxyphenylacetate, p-benzylphenol,hydroquinone-mono-benzyl ether or the like.

The water soluble binders include, by way of illustration but notlimitation, for example, polyvinyl alcohol, hydroxyethyl cellulose,carboxymethyl cellulose, salts of styrene-maleic anhydride copolymers,styrene-butadiene emulsions, vinyl acetate-maleic anhydride emulsions,polyacrylates, polyacrylamide, starches, casein and gum arabic.

The fillers include, for example, clay, talc, kaolin, satin white,titanium oxide, calcium carbonate, magnesium carbonate, barium sulfate,magnesium silicate and aluminum silicate, etc.

The sensitizers include, for example, higher fatty acid amides such as;benzamide, stearic anilide, acetoacetic anilide, thioacetoanilide;esters such as dimethyl phthalate, dibenzyl terephthalate, dibenzylisophthalate; diethers of bisphenol S, e.g.,4,4'-dimethoxydiphenylsulfone, 4-iso-propoxy-4'-n-butoxydiphenylsulfone,4,4'-dibutoxydiphenylsulfone,4,4'-di-n-(or iso-)pentyloxydiphenylsulfone and the like; diphenylamine, carbazole,2,3-di-m-tolylbutane, 4-benzylbiphenyl, 4,4'-dimethylbiphenyl anddi-β-naphthylphenylenediamine.

The dispersing agents include, for example, sulfosuccinic acid esterssuch as dioctyl sodium sulfosuccinate; sodium dodecylbenzenesulfonate;sodium lauryl sulfonate; and salts of fatty acid. The colored imagestabilizers include, for example, salicyclic acid derivatives, metalsalts (particularly zinc salt) of oxynaphthonic acid derivatives andother water-insoluble zinc compounds. The antioxidants include, forexample, 2,2'-methylenebis(4-methyl-6-tert-butylphenol),2,2'-methylenebis(4-ethyl-6-tert-butylphenol),4,4'-propylmethylene-bis(3-methyl-6-tertbutylphenol) and4,4'-thiobis(2-tert-butyl-5-methylphenol). The desensitizers include,for example, aliphatic higher alcohols, polyethylene glycol andguanidine derivatives. The anti-tack agents include, for example,stearic acid, zinc stearate, calcium stearate, carnauba wax, paraffinwax and ester wax, etc.

Following substantially the same manner as in the case of conventionalfluoran compounds, the fluoran compounds of this invention can be usedto prepare pressure-sensitive copying papers in accordance with suchprocedures as disclosed in U.S. Pat. Nos. 2,548,365, 2,548,366,2,800,457 and 2,800,458, Japanese Patent L-O-P Publn. No. 112041/1983 or139738/1983. Developers may be those as previously known, for example,inorganic acidic substances such as acid clay, activated clay,attapulgite, bentonite, colloidal silica, aluminum silicate, magnesiumsilicate, zinc silicate, tin silicate, calcined kaolin and talc;aliphatic carboxylic acids such as oxalic acid, maleic acid, tartaricacid, citric acid, succinic acid and stearic acid; aromatic carboxylicacids such as benzoic acid, p-tert-butylbenzoic acid, phthalic acid,gallic acid, salicyclic acid, 3-isopropylsalicyclic acid,3-phenylsalicyclic acid, 3-cyclohexylsalicyclic acid,3,5-di-tert-butylsalicyclic acid, 3-methyl-5-benzylsalicyclic acid,3-phenyl-5-(2,2-dimethylbenzyl)salicyclic acid, 3,5-di-(2-methylbenzyl)salicyclic acid and 2-hydroxy-1-benzyl-3-naphthoic acid; salts of thesearomatic carboxylic acids with such metals as zinc, magnesium, aluminum,titanium and the like; phenol resin type developers such asp-phenylphenol-formalin resins and p-butylphenol-acetylene resins; andmixtures of these phenol resin type developers and the above-mentionedmetal salts of aromatic carboxylic acids.

The fluoran compounds of this invention can be used in heat-sensitivetransfer in accordance with such procedures as disclosed in JapanesePatent L-O-P Publns. Nos. 212985/1983, 33185/1984, 42995/1984 or225986/1984 in electro thermo heat-sensitive recording papers inaccordance with such procedures, for example, as dislcosed in JapanesePatent L-O-P Publns. Nos. 96137/1973, 101935/1973 or 11344/1974, and inelectrophotography in accordance with such procedures, for example, asdisclosed in Japanese Patent L-O-P Publns. Nos. 24530/1977 or56932/1977.

The fluoran compounds of this invention can be used, furthermore, inphotosensitive recording papers in accordance with such procedures, forexmple, as disclosed in Japanese Patent Publns. Nos. 24188/1963,10550/1970 and 45978/1974, Japanese Patent L-O-P Publns. Nos.80120/1975, 126228/1975, 141633/1975 or 147829/1979; in ultrasonic waverecording papers in accordance with a procedure as disclosed in FrenchPat. No. 2,120,922; in electron recording papers in accordance with aprocedure as disclosed in Belgian Pat. No. 7,959,986; in electrostaticrecording papers in accordance with a procedure as disclosed in JapanesePatent Publn. No. 3932/1974; and in photosensitive printing materials inaccordance with a procedure as disclosed in Japanese Patent L-O-P Publn.No. 12104/1973.

In addition to the applications as mentioned above, the fluorancompounds of this invention can also be used as a color formingcomponent in a composition which color change occurs reversibly(color⃡the colorless) under the influence of temperature as disclosed,for example in Japanese Patent L-O-P Publns. Nos. 75991/1975 and219289/1985, by using in admixture therewith one or more compoundsselected from a compound having a phenolic hydroxyl group and the metalsalts thereof, an aromatic carboxylic acid and the metal salts thereof,an aliphatic carboxylic acid of 2 to 5 carbon atoms and the metal saltsthereof, and an acid phosphoric ester and the metal salts thereof, andone or more compounds selected from alcohols, esters, ketones, ethersand acid amides. The compound having a phenolic hydroxyl group includesthe phenolic compounds used as the color developer in the heat-sensitiverecording papers or the phenol resins used as the color developer in thepressure-sensitive recording papers, but not limiting thereto. Also, themetal salts of said compound include salts of calcium, magnesium, zinc,aluminium, tin, titanium, etc., but not limiting thereto. The aromaticand aliphatic carboxylic acids include benzoic acid, toluic acid,p-tert.-butylbenzoic acid, chlorobenzoic acid, gallic acid, phthalicacid, naphthoic acid, maleic acid, fumaric acid, and the like, and themetal salts thereof include salts of calcium, magnesium, zinc, aluminum,tin, titanium and the like, but not limiting thereto. The acidphosphoric ester includes those in which a phosphate group is attachedto an alkyl group which may be branched, an alkenyl group, an alkynylgroup, a cycloalkyl group and an aryl group, and the derivativesthereof. The alcohols include a monohydric alcohol such as octylalcohol, nonyl alcohol, decyl alcohol, lauryl alcohol, myristyl alcohol,cetyl alcohol, palmityl alcohol, stearyl alcohol, dococyl alcohol, oleylalcohol and benzyl alcohol, and a polyhydric alcohol such as ethyleneglycol, diethylene glycol, polyethylene glycol, polypropylene glycol,pentaerythritol and sorbitol. The esters include methyl stearate, butylstearate, triglyceride of 12-hydroxystearic acid, lauryl myristate,octyl caproate, insect wax and the like. The ketones include diisobutylketone, acetophenone, diphenyl ketone and the like. The acid amidesinclude caprylamide, laurylamide, myristylamide, palmitylamide,stearylamide, oleylamide, stearylanilide and the like, but not limitingthereto.

The following exmaples (preparative and use examples) and comparativeexamples are presented, but the present invention is not limitedthereto.

EXAMPLE 1 (Preparative Example)

20.0 g of o-(4-N-isobutyl-ethylamino-2-hydroxybenzoyl)benzoic acid and8.4 g of 4-chloro-3-methylphenol were added to 110 g of 85% sulfuricacid and continued to stir at temperatures of 120°-125° C. for 4 hours,cooled, and poured into iced water. The reaction product wasprecipitated with addition of a caustic soda solution. The precipitatewas removed by filtration, washed with water, heated while stirringtogether with 88 ml of water, 5 g of caustic soda and 300 ml of toluene,refluxed for 30 minutes, and the mixture was then cooled and allowed tostand. After removal of an aqueous phase, the toluene phase was washedwith a 3.5% aqueous caustic soda solution and water, small amounts ofprecipitate formed was filtered out, 250 ml of toluene was distilledoff, and the residue was cooled. Crystals precipitated were removed byfiltration, washed with small amounts of toluene, and then dried to give20.1 g of 3-N-isobutyl-ethylamino-6-methyl-7-chlorofluoran as paleorange white fine crystals, m.p. 186.2°-187.8° C.

EXAMPLE 2 (Preparative Example)

Substantially the same procedure described in Example 1 was repeatedexcept that 7.5 g of 4-chlorophenol were used in place of the4-chloro-3-methylphenol, to prepare 19.0 g of3-N-isobutylethylamino-7-chlorofluoran (compound 2) as slight orangewhite fine crystals, m.p. 149.1°-150.6° C.

EXAMPLES 3-6 (Preparative Examples)

Substantially the same procedure as in Example 1 was repeated exceptthat in place of the 4-chloro-3-methylphenol, there were used,respectively;

    ______________________________________                                        3,4-dichlorophenol                                                                             9.6         g or                                             4-tert-pentylphenol                                                                            9.6         g or                                             β-naphthol  8.5         g or                                             6-bromo-2-naphthol                                                                             13.1        g,                                               ______________________________________                                    

to prepare the following compounds, respectively;

21.4 g of 3-N-isobutyl-ethylamino-6,7-dichlorofluoran (compound 3) (m.p.155.6°-158.0° C., pale peach white fine crystals),

11.7 g of 3-N-isobutyl-ethylamino-7-tert-pentylfluoran (compound 4)(m.p. 185°-186.4° C., pale peach white fine crystals),

17.5 g of 3-N-isobutyl-ethylamino-7,8-benzofluoran (compound 5) (m.p.192.7°-193.7° C., slightly orange white fine crystals), and

21.4 g of a fluoran compound (compound 6) of the formula, ##STR20##(m.p. 188.0°-189.8° C., pale peach white fine crystals)

EXAMPLE 7 (Preparative Example)

20.0 g of o-(4-N-isopentyl-ethylamino-2-hydroxybenzoyl)benzoic acid and8.0 g of 4-chloro-3-methylphenol was added to 120 g of 85% sulfuric acidand continued to stir at temperatures of 120°-125° C. for 4 hours.Thereafter, substantially the same treatment as in Example 1 gave 21.8 gof 3-N-isopentyl-ethylamino-6-methyl-7-chlorofluoran (compound 7) aspale peach crystals, m.p. 156.5°-159.0° C.

EXAMPLE 8 (Preparative Example)

Substantially the same procedure as in Example 7, was repeated exceptthat 7.2 g of 4-chlorophenol were used in place of the4-chloro-3-methylphenol, to prepare 21.5 g of3-N-isopentyl-ethylamino-7-chlorofluoran (compound 8) as slight peachwhite crystals, m.p. 149.0°-151.0° C.

EXAMPLE 9 (Preparative Example)

Substantially the same procedure as in Example 1 was repeated but using7.2 g of 3-ethylphenol in place of the 4-chloro-3-methylphenol. Evenafter distilling off the toluene, however, no crystal of the endproduct, 3-N-isobutylethylamino-6-ethylfluoran was precipitated out,leaving only a liquid product as a residue, and therefore the residuewas subjected to purification by thin-layer chromatography. That is,using a thin-layer plate, Art. 5745 of Merk Co., Ltd. forchromatography, the residue was developed with chloroform:ethyl acetate(3:1) as a developing solvent. The portions developed in red color werescraped and extracted with methanol:toluene (1:1). The solvent wasdistilled off, and the residue was again extracted with toluene, andtoluene was substantially distilled off but no crystal was obtained fromthe residue. The residue was subjected again to the above-mentionedthin-layer chromatography and to the steps that followed, but no crystalwas obtained. Therefore recrystallizations of the residue from isopropylalcohol, toluene, n-hexane, ligroin and methanol were tried, but it wasnot successful leaving only a substance which was slightly yellowish andviscous at ordinary temperatures and which solidified at a temperatureof -20° C. Analysis of this substance by NMR indicated that thesubstance is the end product of 3-N-isobutyl-ethylamino-6-ethylfluoran(compound 9). The NMR spectrum is shown in the FIGURE.

EXAMPLE 10 (Preparative Example)

Substantially the same procedure as in Example 1 was repeated but using8.5 g of α-naphthol in place of the 4-chloro-3-methylphenol, to prepare14.9 g of 3-N-isobutylethylamino-5,6-benzofluoran (compound 10) as whitefine crystals, m.p. 158.8°-160.7° C.

EXAMPLE 11 (Heat-sensitive recording paper)

3.5 g of 3-N-isobutyl-ethylamino-6-methyl-7-chlorofluoran, 41.5 g of a15% aqueous solution of polyvinyl alcohol (KURARAY-105, produced andsold by Kuraray Co., Ltd.), 15.0 g of clay (UW-90, produced and sold byEngelhard) and 40.0 g of water were charged, together with 150 g ofglass beads (1-1.5 mm in diameter), into a 250 ml polyethylene bottle,the bottle was sealed and placed to a paint conditioner manufactured andsold by Red Devil Co. The bottle was shaked at a rate of 630 times/minfor 5 hours, and thereafter the beads were removed to obtain an aqueoussuspension of 3-N-isobutyl-ethylamino-6-methyl-7-chlorofluoran(suspension A).

Separately, 10.5 g of bisphenol A as a color developer, 41.5 g of a 15%aqueous solution of polyvinyl alcohol (same as above), 8.0 g of clay(same as above) and 40.0 g of water were charged, together with 150 g ofglass beads (same as above), into a 250 ml polyethylene bottle, and thebottle was sealed. The bottle was shaked with the paint conditioner at arate of 630 times/min for 8 hours, and the glass beads were removedtherefrom to prepare an aqueous suspension of bisphenol A (suspensionB).

The suspensions A and B, each 10 g, were mixed together, and the mixturewas stirred for 20 minutes to prepare a coating liquid.

This coating liquid was coated with wire rod No. 12 on a white paper anddried for 2 minutes with air kept at 60° C. to prepare heat-sensitiverecording paper I.

The coated surface of the heat-sensitive recording paper thus obtainedwas heated (1 kg/cm²) with a heat gradient tester (manufactured and soldby Toyo Seiki Seisakusho K.K.) at a temperature of 95° C., 100° C., 110°C., 120° C., 130° C., 150° C. and 180° C. for 5 seconds and thereby todevelop color. The color hue was vermilion. The color density wasmeasured with a Macbeth reflective densitometer (a filter used wasWratten #58). The measured values are shown in Table 2 above.

COMPARATIVE EXAMPLE 1

Substantially the same procedure as in Example 11 was repeated exceptthat 3-diethylamino-6-methyl-7-chlorofluoran was used in place of the3-N-isobutyl-ethylamino-6-methyl-7-chlorofluoran used in Example 11, toprepare heat-sensitive recording paper (II) which was then allowed todevelop color (vermilion). The density of the developed color wasmeasured. The measured values are shown in Table 2 above.

EXAMPLE 12 (Heat-sensitive recording paper)

Substantially the same procedure as in Example 11 was repeated exceptthat 3.5 g of 3-N-isobutyl-ethylamino-7-chlorofluoran was used as afluoran compound and benzyl p-hydroxybenzoate was used as a colordeveloper, to prepare heat-sensitive recording paper (III) which wasallowed to develop color (color development temperature: 85° C., 90° C.,95° C., 100° C., 110° C., 120° C. and 130° C.) (The hue of the developedcolor was vermilion). The density of the developed color was measured.The measured values are shown in Table 3 above.

COMPARATIVE EXAMPLE 2

Except that 3-diethylamino-7-chlorofluoran was used in place of the3-N-isobutyl-ethylamino-7-chlorofluoran used in Example 12,substantially the same procedure as in Example 12 was repeated toprepare heat-sensitive recording paper (IV) which was allowed to developcolor (vermilion). The density of the developed color was measured. Themeasured values are shown in Table 3 above.

EXAMPLE 13 (Heat-sensitive recording paper)

Except that in place of the fluoran compound, 3.5 g of3-N-isobutyl-ethylamino-7-chlorofluoran used in Example 12, a mixture of3.32 g of 3-N-methyl-cyclohexylamino-6-methyl-7-phenylaminofluoran(black color forming chromogenic dye) and 0.18 g of3-N-isobutyl-ethylamino-7-chlorofluoran was used, substantially the sameprocedure as in Example 12 was repeated to prepare a heat-sensitiverecording paper which was then heated with a heat gradient tester at atemperature of 130° C. for 5 seconds to develop color.

Furthermore, a heat-sensitive recording paper was prepared and allowedto develop color in the manner similar to the above, but using 3.5 g of3-N-methyl-cyclohexylamino-6-methyl-7-phenylaminofluoran with no use of3-N-isobutylethylamino-7-chlorofluoran.

In the heat-sensitive recording paper with no use of3-N-isobutyl-ethylamino-7-chlorofluoran, the color developed wasslightly greenish black, whereas the color developed in theheat-sensitive recording paper using said fluoran compound was blackfree from greenish tinge.

EXAMPLE 14 (Heat-sensitive recording paper)

Except that in place of the fluoran compound, 3.5 g of3-N-isobutyl-ethylamino-7-chlorofluoran used in Example 12, a mixture of2.95 g of 3-diethylamino-6-chloro-7-phenylaminofluoran (black colorforming chromogenic dye) and 0.55 g of3-N-isobutyl-ethylamino-7-chlorofluoran was used, substantially the sameprocedure as in Example 12 was repeated to prepare a heat-sensitiverecording paper which was then heated with a heat gradient tester at atemperature of 130° C. for 5 seconds to develop color.

Furthermore, a heat-sensitive recording paper was prepared and allowedto develop color in the manner similar to the above, but using 3.5 g of3-diethylamino-6-chloro-7-phenylaminofluoran without using at all3-N-isobutyl-ethylamino-7-chlorofluoran.

In the heat-sensitive recording paper with no use of3-N-isobutyl-ethylamino-7-chlorofluoran, the color developed was blackwith somewhat strong greenish tinge, whereas in the heat-sensitiverecording paper using said fluoran compound, the color developed wasblack substantially free from greenish tinge.

EXAMPLE 15 (Pressure-sensitive copying paper)

1.0 g of 3-N-isobutyl-ethylamino-7,8-benzofluoran was dissolved in 20 gof alkyl naphthalene at 90° C. to obtain a solution (Solution A).Separately, 2.0 g of gelatin (isoelectric point 8.0) and 0.5 g ofcarboxymethyl cellulose were completely dissolved in 120 ml of water toobtain a solution (Solution B). Subsequently, Solutions A and B weremixed at 50°-60° C., and stirred at high speed to emulsify, and theemulsified product was adjusted to pH 8.5-9.0. Thereafter, theemulsified product was stirred at high speed for 20 minutes, the pH wasgradually lowered to pH 3.8 with dilute acetic acid, and cooled withstirring to 5°-10° C. To the cooled emulsified product was added 6 g ofa 37% aqueous formalin solution, and the mixture was stirred at 10°-20°C. for further 1 hour.

Subsequently, the emulsion was adjusted to pH 9.0 with an aqueous sodiumhydroxide solution (5%). This emulsion was gently stirred for severalhours to obtain an emulsion containing very fine microcapsules coveredwith gel films of carboxymethyl cellulose and gelatin, each capsulecontaining inside an alkyl naphthalene solution of3-N-isobutyl-ethylamino-7,8-benzofluoran. This emulsion was coated on apaper and dried to prepare a top sheet of pressure-sensitive paper.Separately, phenol-formalin resin was coated on a paper and dried toprepare a bottom sheet. The coated surface of the top sheet was placedon the coated surface of the bottom sheet, and letters were written onthe uncoated surface of the top sheet, whereby deep pink-colored lettersappeared very quickly on the coated surface of the bottom sheet.

With the bottom sheet for pressure-sensitive copying paper coated withclay in place of the phenol-formalin resin, deep pink-colored lettersappeared likewise.

EXAMPLE 16 (Pressure-sensitive copying paper)

There were mixed 3.0 g of3-N-isobutyl-ethylamino-6-methyl-7-chlorofluoran, 6.0 g of3-diethylamino-5-methyl-7-dibenzylaminofluoran (green color formingchromogenic dye), 0.5 g of crystal violet lactone[3,3-bis(4-dimethylaminophenyl)-6-dimethylaminophthalide](blue colorforming chromogenic dye) and 0.5 g of benzoyl leucomethylene blue (bluecolor forming chromogenic dye). This mixture (4.0 g) was mixed with 50.0g of alkyl diphenylmethane (Hizole SAS 296, produced and sold by NissekiKagaku K.K.) and 36.0 g of diisopropyl naphthalene (KMC-113, producedand sold by Kureha Kagaku K.K.), and heated to dissolve and stirred at90° C. for 10 minutes and cooled (Solution A).

Separately, 30.0 g of a 10% aqueous solution of a sulfonic acid-modifiedpolyvinyl alcohol (Gosenol CKS-50, produced and sold by The NipponSynthetic Chemical Industry Co., Ltd., average polymerization degreeabout 300, saponification degree 97%, and modification degree 10 mol %),15.0 g of a 10% aqueous solution of ethylene-maleic anhydride copolymer(EMA-31, produced and sold by Monsanto Co.) and 67.5 ml of water weremixed and added with further 5.0 g of urea and 0.5 g of resorcinol toprepare a solution. The solution was adjusted to pH 3.4 with a 20%aqueous caustic soda solution (Solution B).

Solution A was added to Solution B and stirred with a homomixer at 9,000rpm for 2 minutes to prepare an emulsion. The emulsion was then chargedwith 14.0 g of a 35% aqueous formalin solution and stirred at 9,000 rpmfor 3 minutes. Thereafter, the emulsion was stirred at 8000 rpm andelevated temperatures of 60°-65° C. for 60 minutes. The stirring withthe homomixer was ceased, the emulsion was cooled to 40° C. and adjustedto pH 7.5 with the addition of 28% ammonia water to prepare a suspensionof microcapsules.

27.0 g of this suspension (kept at a temperature below 30° C.), 3.5 g ofwheat starch, 8.5 g of a 8% wheat starch solution and 34.0 ml of waterwere mixed and stirred with a stirrer at room temperatures for 30minutes to prepare a coating solution.

The coating solution was coated with a wire bar No. 12 on a white paperand dried for 3 minutes with air kept at 60° C. to prepare a top sheetof pressure-sensitive copying paper.

The coated surface of the top sheet was placed in the same manner as inExample 15 on the coated surface of the bottom sheet, and letters werewritten on the surface of the top sheet, whereby black-colored lettersappeared very quickly on the coated surface of the bottom sheet.

EXAMPLE 17 (Pressure-sensitive copying paper)

A top sheet of pressure-sensitive copying paper was prepared insubstantially the same manner as in Example 16, but using 4.0 g of3-N-isobutyl-ethylamino-5,6-benzofluoran in place of 4.0 g of themixture of 4 kinds of chromogenic dyes used in Example 16. This topsheet was placed on the bottom sheet in the same manner as in Example15, and letters were written on the surface of the top sheet, wherebypink-colored letters appeared very quickly on the coated surface of thebottom sheet.

EXAMPLE 18 (Use Example)

In 100 ml of toluene were dissolved 0.4 g of3-N-methyl-cyclohexylamino-6-methyl-7-phenylaminofluoran, 0.15 g of3-N-isobutyl-ethylamino-6-methyl-7-chlorofluoran, 0.35 g of3-diethylamino-5-methyl-7-dibenzylaminofluoran and 0.1 g of benzoylleucomethylene blue.

This toluene solution was applied to a writing brush, and a drawing wasdepicted with the brush on the clay coated surface of a bottom sheet forpressure-sensitive copying paper, whereby a beautiful black drawingappeared thereon.

EXAMPLE 19 (Heat transfer paper)

10.0 g of 3-N-isobutyl-ethylamino-7,8-benzofluoran, 1.0 g of finelydivided silica, and 100 g of polystyrene resin (m.p. 100° C.) and 100 gof methyl ethyl ketone were charged with 100 g of glass beads into a 250ml polyethylene bottle, and the bottle was sealed and shaked at a rateof 630 times/min. with a paint conditioner for 5 hours, and the glassbeads were then, removed therefrom to prepare a suspension containingthe fluoran compound.

Separately, 20.0 g of benzyl 4-hydroxybenzoate, 10.0 g of finely dividedsilica, 3.0 g of polyvinyl alcohol and 100 g of water were chargedtogether with 100 g of glass beads into a 250 ml polyethylene bottle,and the bottle was sealed and shaked at a rate of 630 times/min. with apaint conditioner for 8 hours. Thereafter, the glass beads were removedto prepare a color developer suspension.

The above-mentioned fluoran compound containing suspension was coatedwith a wire rod on a condenser paper and then dried to prepare atransfer sheet, and the color developer suspension was coated with awire rod on a high quality paper and then dried to prepare a receivingpaper.

The coated surface of the receiving sheet was placed on the coatedsurface of the transfer paper, and the transfer sheet was heated fromthe back side with a heat pen. A clear pink-colored image appeared onthe coated surface of the receiving sheet corresponding to the heatedportion of the transfer sheet.

EXAMPLE 20 (Thermo-sensitive, reversible color changing composition)

10.0 g of 3-N-isobutyl-ethylamino-7,8-benzofluoran, 10.0 g of bisphenolA and 250 g of cetyl alcohol were mixed, heated to about 80° C. anddissolved to prepare a pink solution. Cooling of the solution resultedin substantially colorless at approximately 40° C.

EXAMPLE 21 (Microcapsule containing the composition of Example 20)

In 30 g of color changing composition prepared in Example 20 weredissolved under heat 6.0 g of stylene monomer, 0.6 g of divinylbenzeneand 10 mg of benzoyl peroxide. The solution was added dropwise to 150 gof 2% aqueous solution of gum arabic and stirred so as to provide finedroplets. Continuous stirring of 5 hours at about 60° C. gave anemulsion of microcapsule containing the above composition. The emulsionwas coated onto a white paper and dried to prepare a thermo-sensitive,reversible color changing material. The material was colorless attemperatures lower than about 40° C. and formed beautiful pink color attemperatures higher than 40° C.

What is claimed is:
 1. A chromogenic recording material which comprisesa substrate, a fluoran compound of the formula ##STR21## wherein R is anisobutyl or isopentyl group, R₁ is hydrogen, a halogen atom or an alkylgroup, R₂ is hydrogen, a halogen atom or an alkyl group, R₃ is hydrogen,and R₄ is hydrogen, or R₄ and R₁ as well as R₂ and R₃, when takentogether with the carbon atoms to which they are attached, form asubstituted or unsubstituted benzene ring wherein the substituent is ahalogen atom, as a color forming component, and a color developercapable of causing the color formation of the fluoran compound.
 2. Thechromogenic recording material of claim 1 wherein the color formingcomponent is selected from3-N-isobutyl-ethylamino-6-methyl-7-chlorofluoran,3-N-isobutyl-ethylamino-7-chlorofluoran,3-N-isobutylethylamino-7,8-benzofluoran,3-N-isopentyl-ethylamino-6-methyl-7-chlorofluoran or3-N-isopentyl-ethylamino-6-chlorofluoran.
 3. The chromogenic recordingmaterial of claim 2 which firther comprises as a color forming componentat least one of black color forming chromogenic fluoran compounds. 4.The chromogenic recording material of claim 3 which is heat-sensitiverecording papers.
 5. The chromogenic recording material of claim 3 whichis pressure-sensitive recording papers.
 6. The chromogenic recordingmaterial of claim 3 which is heat-transfer chromogenic recording papers.7. The chromogenic recording material of claim 8 which is heat-transferchromogenic recording papers.
 8. The chromogenic recording material ofclaim 2 which further comprises as a color forming component at leastone of a green color forming chromogenic compound and a blue colorforming chromogenic compound.
 9. The chromogenic recording material ofclaim 8 which is heat-sensitive recording papers.
 10. The chromogenicrecording material of claim 8 which is pressure-sensitive recordingpapers.
 11. The chromogenic recording material of claim 2 which isheat-sensitive recording papers.
 12. The chromogenic recording materialof claim 2 which is pressure-sensitive recording papers.
 13. Thechromogenic recording material of claim 2 which is heat-transferchromogenic recording papers.
 14. The chromogenic recording material ofclaim 1 wherein the color developer is selected from bisphenolcompounds, 4-hydroxybenzoic acid esters, hydroxysulfones or4-hydroxyphthalic acids.
 15. The chromogenic recording material of claim14 which further comprises as a color forming component at least one ofblack color forming chromogenic fluoran compounds.
 16. The chromogenicrecording material of claim 15 which is heat-sensitive recording papers.17. The chromogenic recording material of claim 15 which ispressure-sensitive recording papers.
 18. The chromogenic recordingmaterial of claim 15 which is heat-transfer chromogenic recordingpapers.
 19. The chromogenic recording material of claim 14 which furthercomprises as a color forming component at least one of a green colorforming chromogenic compound and a blue color forming chromogeniccompound.
 20. The chromogenic recording material of claim 19 which isheat-sensitive recording papers.
 21. The chromogenic recording materialof claim 19 which is pressure-sensitive recording papers.
 22. Thechromogenic recording material of claim 19 which is heat-transferchromogenic recording papers.
 23. The chromogenic recording material ofclaim 14 which is heat-sensitive recording papers.
 24. The chromogenicrecording material of claim 14 which is heat-transfer chromogenicrecording papers.
 25. The chromogenic recording material of claim 1wherein the color developer is selected from inorganic acid substances,aliphatic carboxylic acids, aromatic carboxylic acids, metal salts ofaromatic carboxylic acids, phenol resin type developers (such asp-phenylphenol-formalin resin and p-butyl-phenol-acetylene resin), ormixtures of phenol resin type developers and metal salts of aromaticcarboxylic acids.
 26. The chromogenic recording material of claim 25which further comprises as a color forming component at least one ofblack color forming chromogenic fluoran compounds.
 27. The chromogenicrecording material of claim 26 which is heat-sensitive recording papers.28. The chromogenic recording material of claim 26 which ispressure-sensitive recording papers.
 29. The chromogenic recordingmaterial of claim 26 which is heat-transfer chromogenic recordingpapers.
 30. The chromogenic recording material of claim 25 which ispressure-sensitive recording papers.
 31. The chromogenic recordingmaterial of claim 25 which further comprises as a color formingcomponent at least one of a green color forming chromogenic compound anda blue color forming chromogenic compound.
 32. The chromogenic recordingmaterial of claim 31 which is heat-sensitive recording papers.
 33. Thechromogenic recording material of claim 31 which is pressure-sensitiverecording papers.
 34. The chromogenic recording material of claim 31which is heat-transfer chromogenic recording papers.
 35. The chromogenicrecording material of claim 25 which is heat-transfer chromogenicrecording papers.
 36. The chromogenic recording material of claim 1wherein the substrate is selected from the paper synthetic fiber fabric,synthetic paper or synthetic resin sheet.
 37. The chromogenic recordingmaterial of claim 36 which further comprises as a color formingcomponent at least one of black color forming chromogenic fluorancompounds.
 38. The chromogenic recording material of claim 37 which isheat-sensitive recording papers.
 39. The chromogenic recording materialof claim 37 which is pressure-sensitive recording papers.
 40. Thechromogenic recording material of claim 37 which is heat-transferchromogenic recording papers.
 41. The chromogenic recording material ofclaim 36 which is heat-sensitive recording papers.
 42. The chromogenicrecording material of claim 36 which is pressure-sensitive recordingpapers.
 43. The chromogenic recording material of claim 36 which furthercomprises as a color forming component at least one of a green colorchromogenic compound and a blue color forming chromogenic compound. 44.The chromogenic recording material of claim 43 which is heat-sensitiverecording papers.
 45. The chromogenic recording material of claim 43which is pressure-sensitive recording papers.
 46. The chromogenicrecording material of claim 43 which is heat-transfer chromogenicrecording papers.
 47. The chromogenic recording material of claim 36which is heat-transfer chromogenic recording papers.
 48. The chromogenicreading material of claim 1 which further comprises as a color formingcomponent at least one of the black color forming chromogenic fluorancompounds.
 49. The chromogenic recording material of claim 48 which isheat-sensitive recording papers.
 50. The chromogenic recording materialof claim 48 which is pressure-sensitive recording papers.
 51. Thechromogenic recording material of claim 48 which is heat-transferchromogenic recording papers.
 52. The chromogenic recording material ofclaim 1 which further comprises as a color forming component at leastone of a green color forming chromogenic compound.
 53. The chromogenicrecording material of claim 52 which is heat-sensitive recording papers.54. The chromogenic recording material of claim 52 which ispressure-sensitive recording papers.
 55. The chromogenic recordingmaterial of claim 52 which is heat-transfer chromogenic recordingpapers.
 56. The chromogenic recording material of claim 1 which isheat-sensitive recording papers.
 57. The chromogenic recording materialof claim 1 which is pressure-sensitive recording papers.
 58. Thechromogenic recording material of claim 1 which is heat-transferchromogenic recording papers.